David Cameron accused world leaders of “contracting out” their morality by ducking military decisions on Syria and leaving the fate of civilians to the United Nations, where Russia wields a veto.

In remarks at the end of a bitterly divided G20 summit in St Petersberg, the Prime Minister criticised a “dangerous doctrine” held by some leaders that military action must always be backed by a Security Council resolution.

“If we’re saying there can only be a response if the UN Security Council votes positively, we are in fact contracting our foreign policy, our morality, to the potential of a Russian veto. I think that is a very misguided approach,” Mr Cameron said.

His comments, making a moral and legal case for Barack Obama to go it alone, followed a dinner where Vladimir Putin rallied opponents of military strikes intended to punish Bashar al-Assad’s regime for suspected chemical weapons attacks.

At his post-summit press conference, Mr Putin read out a list of those he said were opposing action. “Who was condemning and opposing that way of action? The Russian Federation, India, China, Indonesia, Argentina, Brazil, South Africa, Italy,” he said.

“The world cannot wait for endless failed processes that can only lead to increased suffering in Syria and regional instability,” they said.

Mr Obama and Mr Putin held a surprise private meeting towards the end of the summit to clear the air. Mr Obama said it was a “candid and constructive conversation” but afterwards the two appeared to be as far apart as ever.

In his press conference Mr Obama claimed there was growing recognition that “the world cannot stand idly by” in the face of chemical weapons. “I would greatly prefer working through multilateral channels and the United Nations to get this done,” he said. “But... what I believe in even more deeply… [is] that when there’s a breach this brazen and the international community is paralysed and frozen and doesn’t act, then that makes for a more dangerous world.”

But Mr Putin insisted that “those who act unilaterally violate the law”.

“Small countries in the modern world feel increasingly vulnerable and insecure,” he said. “One starts getting the impression that a more powerful country can at any time and at its own discretion use force against them.”

Earlier Mr Cameron said arguments did “flare up at the dinner” over the legality of attacks without Security Council backing. But he said: “One of the frustrations of last night is you have countries, including Security Council permanent members, saying this must all be decided by the UN Security Council – yet they are the very countries that are blocking any action and have been blocking resolutions for two and a half years.”

Mr Cameron praised Mr Obama’s stand, saying the US leader “is no way seen as a war-monger”. And he dismissed Mr Putin’s claim that Syrian rebels might have launched the Sarin attack as “miles away from what I think the truth is”.

Hopes that the G20 could reach agreement were dashed as the delegates dined on caviar, blini and venison at the Peterhof Palace on Thursday night, followed by an hour-long “musical fountain show”.

Mr Obama arrived 30 minutes late and chatted with Mr Cameron, smiling, before they sat down. Mr Putin let every leader have a say but ensured that the last four speakers were known opponents of military strikes, including Argentina’s Cristina Fernández de Kirchner who spoke for a full 30 minutes, prompting some leaders to pull out their translator earpieces and chat among themselves.

At a 35-minute bilateral meeting with Mr Putin in the early hours of yesterday, Mr Cameron raised British concerns about gay rights in Russia, where laws banning so-called homosexual propaganda have caused anger. Mr Putin gave a commitment that gay athletes and spectators would not be harassed at the Winter Olympics, but that did not satisfy Mr Cameron, who has asked Russia to respect the rights of all gay people.

Mr Cameron also launched an initiative to obtain safe passage for aid convoys trying to reach refugees after the UN Secretary-General, Ban Ki-Moon, told the G20 that Syria represented a “humanitarian crisis of unprecedented proportions in recent history”.

“The world must do everything within its powers to stop the suffering of the Syrian people,” he said. “Let us use this united recognition of the problem as our starting point for focused and positive action.”

Mr Cameron announced an additional £52m in UK aid for Syria, which will go towards medical training and equipment to help civilians targeted by chemical attacks.

St Petersburg Diary: Wheels within wheels

Behind the wheel

Having had much of his influence at the G20 robbed from him by Parliament before he even arrived, David Cameron seemed glad to get a feeling of power in his hands when he went for a drive around St Petersburg yesterday morning. His spin in an electric car turned out to be the first time Cameron had been behind a wheel in three years, since his security guards have never let him risk the roads of the UK since he became Prime Minister.

Unfashionable lateness

Never one to miss an opportunity to irritate his international friends, Russian Prime Minister Vladimir Putin kept the leaders of G20 countries waiting for several minutes when it came time for the mandatory “family photo” in front of the Constantine Palace yesterday. The assembled presidents and prime ministers accepted his apologetic shrug with thin smiles and gritted teeth.

“A small island”

A Russian official’s jibe dismissing Britain as “a small island no one listens to” led Cameron into a cloyingly passionate defence of the sceptred isle that deserved at least a few bars of “Jerusalem”: “Britain may be a small island, but I would challenge anyone to find a country with a prouder history, a bigger heart or greater resilience,” he declared, possibly waving a fist in the air. He went on: “Britain is an island that helped to abolish slavery, that has invented most of the things worthwhile inventing.”

Tory MP Henry Smith opted for a pithier retort: “Putin really is a tosser,” he wrote on Twitter.

Eric Randolph

Team Obama

Australia Canada, France, Italy, Japan, Republic of Korea, Saudi Arabia, Spain, Turkey, the United Kingdom and the United States of America

President Obama’s support hardened significantly at the end of the summit when a joint statement backing his efforts “to reinforce the prohibition of the use of chemical weapons” was signed by 11 nations. The statement warned: “The world cannot wait for endless failed processes.”

Answering questions from reporters about discussions at the G20, President Putin said: “The opinions didn’t divide 50/50. Who was for military intervention? The US, France, Saudi Arabia, Canada and Turkey. Mr Cameron also was advocating military intervention but the British Parliament was against that. The Chancellor of Germany was also cautious, Germany is not going to participate in any military action.”

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